The subject invention relates to outer shrouds or cylinders for gas turbine engines, and more particularly, to an outer cylinder construction made of a composite of ceramic materials and metallic materials.
In order to operate gas turbine engines more efficiently, turbine inlet temperatures have continually been elevated into temperature ranges greater than 1800.degree.-1900.degree. F. where it is desirable to form the outer shroud components of the gas turbine engine of a high temperature ceramic material that is suitable to contain the elevated temperature combustion gases as they are directed from a high temperature combustor through the turbine stages of the engine. Due to their tolerance to hot gas path temperatures up to approximately 2500.degree. F., ceramic materials generally offer the potential for more efficient engine operation, while permitting reduced cooling air requirements. In addition, a ceramic cylinder also offers the potential for turbine tip clearance control, since the ceramic material is generally less sensitive to thermal distortion as compared to metallic structures.
However, when ceramic materials interface with metallic structures, stresses are generated because of the different reactions of the materials to temperature. It is therefore the object of this invention to construct an assembly which utilizes ceramic materials in direct contact with the hot gases of a turbine engine and to secure the ceramic assembly in a manner which allows for relative movement between ceramic and metallic parts to compensate for thermal growth in the metallic structure.